The present invention relates to a device for transferring a film from a backing tape onto a substrate having backing tape reels arranged next to each other.
In this type of device, the take-up speed of the take-up reel has to be at least as great as the unwinding speed of the supply reel, otherwise loops can form in the take-up film strip of the take-up tape which can impair take-up so much that the device is unusable. When abiding by this speed condition, it has to be taken into account that the respective effective winding diameters of the supply reel and the take-up reel change and therefore the take-up speed is dependent on the respective winding size of the supply reel. To guarantee problem-free take up, a drive connection between the supply reel and the take-up reel has been developed which seeks to take up the backing tape at a speed which is greater than the unwinding speed, a differential gear being provided in the drive connection between the supply reel and the take-up reel which guarantees that the supply and take-up speeds are always equal and that a specific tautness in the backing tape running onto the take-up reel is not exceeded. Such a differential gear can, for example, be formed by a sliding clutch. This guarantees that the backing tape is always wound up with a certain tension, the sliding clutch ensuring that the backing tape cannot rip. Such a differential gear or such a sliding clutch is described for example in DE 42 20 712 C2. In this known device, the supply reel and the take-up reel are arranged in a common plane of rotation. Although this allows a narrow construction to be achieved in the axial direction of the reels, a relatively large construction is required in the radial direction of the reels.
To obtain a small construction in the radial direction, devices which have the supply reel and the take-up reel arranged axially offset with respect to each other and next to each other have already been developed. DE 41 04 331 C2 shows a construction in which the supply reel and the take-up reel are borne on a common rotational axis, a friction element in the form of a foam ring being arranged between the reels to thus form the sliding clutch. Given the constantly changing winding diameters of the reels in the operating mode, it is difficult in such a design to ensure that the take-up speed is always at least as great as the supply speed. Because the reels are arranged axially offset and next to each other, this produces two winding planes for the backing tape which are arranged next to each other. Due to the presence of the backing tape loop extending between the reels and the affiliated application member, the unwinding and winding up of the backing tape onto the reels arranged next to each other is guaranteed. In this known device, the reel diameters have to have dimensions which differ such that the above-described condition is fulfilled. This requires a larger construction in the radial direction.
A design similar to the design described above is provided in a device according to DE 38 37 621 C2 (corresponding to U.S. Pat. No. 5,006,184 to Manusch et al.). In this known design, the differential gear or the sliding clutch is formed by a tooth-wheel drive which works between the reels, the teeth of one of the toothed rings being formed on pliably arranged spring arms so that the speed of the tooth drive can be increased as necessary in the sense of a sliding clutch. Furthermore, the reels may be arranged axially next to each other but the rotational axes of the reels enclose an obtuse angle open towards the application member so that the unwinding backing tape strip and the winding up backing tape stripxe2x80x94seen transversely to the rotational axesxe2x80x94extend at an acute angle towards the application member and therefore the backing tape take-up and supply is improved.
Another device of the type described above with reels which are arranged axially offset next to each other is described in DE 196 09 533 C1 (corresponding to U.S. Pat. No. 6,079,660 to Manusch et al.). In this known embodiment, the reels are in direct abutment on their mutually facing sides but are rotatably mounted about two rotational axes which are radially offset from each another. Both of the reels are formed as hollow reels with a step-up gearing being arranged as a toothed gearing in the free hollow space of the supply reel between the supply reel and an inner pinion. The gearing is formed on a rotating part which protrudes axially beyond the supply reel and has a rotary bearing part in this protruding part on which the take-up reel is rotatably mounted by means of a cylindrical bearing boss. On its circumference, the bearing member has a plurality of spring arms which are elastically prestressed radially against the boss walls of the take-up reel, thus forming a sliding clutch which enables the speed to be balanced, as described above. In this known design, it is necessary, considering the transmission ratio between the supply reel and the rotating part forming the inner toothed wheelwork, for the take-up reel to have a certain minimum diameter. In the design inferred by this publication, the take-up reel is considerably larger than the supply reel. This also makes it necessary to have an enlarged construction in the radial direction.
A device having a construction similar to the construction described above is known in DE 196 11 440 A1 (corresponding to U.S. Pat. No. 5,679,156 to Matsumaru). In this known design, a support wall of an insertion member is arranged between the radially offset and axially adjacent reels, with a step-up gearing not being arranged inside the reel but in the radial offset region between the reels.
It therefore would be desirable to form a device of the type described above such that a better economy of space and also a small, handy design can be achieved.
The present invention provides a compact device for transferring film from a backing strip to a substrate, the device comprising a housing containing a stock of tape, a supply reel, a take-up reel, an application member extending from an opening in the housing, and a gear arrangement between the supply reel and the take-up reel. The tape is supplied from the supply reel, passed over the application member, and rewound onto the take-up reel. The application member presses the tape on an application surface during operation of the device.
In one embodiment, the supply reel and the take-up reel are non-coplanar and the gear arrangement includes a rotating member or rotating part (referenced herein as a rotating member for the sake of convenience without any intent to limit) rotatable about a rotational axis. The rotational axis of the take-up reel can be arranged radially offset relative to the rotational axis of the rotating member. The position of the take-up reel can be radially offset relative to the rotational axis of the rotating member in any direction within the bounds of the possible eccentric arrangement, thus producing a way of adapting to the housing of the device and therefore making it possible to optimally exploit the interior of the housing. A small, compact construction can therefore be achieved. This advantage is particularly beneficial because the device is handled manually when in use and the size range available is therefore limited.
In addition, it is possible to arrange a gear arrangement, a drive connection, or a revolution-regulating gearing (referenced herein as a gear arrangement for the sake of convenience without any intent to limit) between the rotating member and the take-up reel in a simple manner, thus advantageously using the available component size and, where appropriate, also the design as a whole.
The gear arrangement may be arranged between the rotating member and the take-up reel This gearing can be a step-up gearing or a step-down gearing depending on the construction of the device. This embodiment of the invention makes it possible to reach a minimum number of revolutions or a minimum winding speed for the take-up reel in a restricted amount of space. It will be appreciated that, although a change in the number of revolutions can also be achieved with the known gear arrangement, the step-up ratio or the step-down ratio of the gear arrangement is restricted because of the limited amount of space available. In an embodiment of the invention, however, two revolution-regulating gears are present in two spaces located next to each other so that not only a better economy of space, but also a larger speed regulation is achieved. The latter is of particular importance with regard to achieving the smallest possible construction because a small construction also leads to relatively small winding diameters, particularly of the take-up reel. This means that the embodiment according to the invention also makes it possible to obtain a required minimum number of revolutions or minimum winding speed when the take-up reel has small dimensions.
A particularly simple embodiment is produced when the gear present between the rotating member and the take-up reel is a friction wheel gear. Such a gear is not just characterized by a simple and inexpensive construction and a reliable function, it also allows the differential gear or the sliding clutch to be integrated in a friction wheel coupling, thus obtaining a particularly simple, inexpensive, and yet reliably functioning embodiment.
The friction wheel gear is particularly simply configured when, of two radial walls which abut each other with axial stress, one or both friction wheel walls are resiliently flexible and bear upon each other with an inherent elastic stress. This type of embodiment does not require any special components, e.g., a spring, to produce the elastic pressure for the desired conveyance. The tension required for the friction is achieved in the mounting of the rotating member of the second reel by the frictional stress being caused in the predetermined positions of the parts as a result of the radial walls having dimensions which are smaller or larger than specified.